The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Radiography is one of the most helpful and common diagnostic tools available to dental practitioners. X-rays usage as a standard diagnostic procedure is well established in the profession. It is important to get as much as possible diagnostic information from X-ray images. A differential diagnosis could be performed using X-ray images. Conventional films are used commonly in radiologic examination to evaluate jaw cysts and odontogenic tumors. X-ray imaging is easy, convenient to use and reproducible method. The equipment is relatively cheap compared with other advanced imaging modalities. The images are easy to read once the observer is trained. They are also simple to store and retrieve. Diagnosis could be performed as soon as the image is taken.
White et al. introduced the Oral Radiographic Deferential Diagnosis (ORAD) program that is based on a questionnaire that was designed to evaluate the clinical and radiographic features of patients with intra-bony lesions using Bayes' theorem, in their work “Computer-aided differential diagnosis of oral radio-graphic lesions”, Dentomaxillofacial Radiol 1989; 18(2):53-9, which is incorporated herein by reference in its entirety. The aim of ORAD program is to assist in lesions identification. Ninety-eight jaw lesions were described by many features such as their prevalence and distribution by race, sex, age, and the presence of pain, size, number, and location of lesions, association with teeth, jocularity, expansion, contents, borders and impact on adjacent teeth, and wherein a menu of sixteen questions is utilized to characterize a specific lesion.
A list of the lesions is introduced as output in order of their estimated probability. In addition, an estimate of the match extent between the lesion and the appearance of each lesion in the knowledge base is calculated. Preliminary tests indicate that ORAD is useful in assisting clinicians in formulating a differential diagnosis.
Radiologists usually analyze X-ray images by extracting features from the border of the lesion, internal structures, placement and resorption of the teeth. Many steps are required to evaluate radiopaque jaw lesion. The first and most important step is to categorize the lesion by its attenuation, and its location with respect to the tooth. These observations are essential for the evaluation of any type of jaw lesion. Then it will be easy to create a proper differential diagnosis. Perilesional halo, growth pattern, bone expansion, and margin as well as the type of lesion—whether it is sclerotic, has ground-glass attenuation, or is mixed lytic and sclerotic are all important features that narrow the differential diagnosis. To explore the “terra incognita” of radiopaque jaw lesions it is important to be aware of the associated clinical features and their demographic distribution, as well as the radiologic approach.
Radiologists are frequently consulted to evaluate a variety of jaw lesions or may incidentally encounter these lesions on routine patient's checkup. It is important to have a diagnostic approach pattern when faced with an unknown jaw lesion. Specific cardinal and additional radiographic criteria on plain film studies are important for differential diagnosis. The location with regard to the adjacent tooth structures within the jaw Cardinal and the density of the lesion are basic radiographic criteria. Other criteria in the jaw lesions evaluation are morphological characteristics, demarcation, periosteal, cortical involvement and soft tissue changes. Lesions could be categorized into two types, namely well-defined and poorly-defined. A well-defined lesion is a tumor representing a distinct radiolucency with a corticated margin. In a poorly defined lesion, the border is readily identified but is not corticated. A diffuse border is characterized by a margin that could not be distinguished and the transitional zone between the lesion and unaffected bone is wide and indistinct. The internal structures indicate the type of trabeculations.
Some jaw lesions have characteristic radiographic appearance such as ameloblastoma which usually appear as a multi-locular cyst like lesion of the jaw (honeycomb), while osteosarcoma appears usually as sunray radiopacity. On the other hand, myxoma is described as delicate filamentous structures that tend to be angular and form square, rectangular or triangular compartments. Some studies called this feature “tennis racquet” appearance. The internal structures are evaluated with reference to these trabeculations.
It is important to provide dentists with the tools that help them to assess their own accuracy at least for common diagnostic problems. A major step in improving dentist's diagnostic accuracy is to identify features on X-ray images correctly and accurately. Accordingly, there is a requirement to provide for an accurate method of performing jaw lesion segmentation.